A ray of light is incident at an angle of 30° to a mirror surface. The angle…
2023
A ray of light is incident at an angle of 30° to a mirror surface. The angle between the normal and the reflected ray is:
Answer: B. 60° — ConceptThe normal is perpendicular to the mirror at the point of incidence. Angles of incidence and reflection are measured from the normal, and the law of…
- A.
30°
- B.
60°
- C.
45°
- D.
More than one of the above
- E.
None of the above
Show answer & explanation
Correct answer: B
Concept
The normal is perpendicular to the mirror at the point of incidence.
Angles of incidence and reflection are measured from the normal, and the law of reflection gives angle of incidence = angle of reflection.
Application
The incident ray makes 30° with the mirror surface.
Therefore, its angle with the normal is 90° − 30° = 60°.
By the law of reflection, the reflected ray also makes 60° with the normal.
Cross-check
The reflected ray at 60° to the normal is 30° to the mirror surface, so the two reference angles add to 90°.
Thus, the angle between the normal and the reflected ray is 60°.